1. Field of the Invention
The present invention relates to a blankmask and a photomask using the same, and more particularly to a blankmask which can achieve a fine pattern of not greater than 32 nm, preferably not greater than 14 nm, and more preferably not greater than 10 nm, and a photomask using the same.
2. Discussion of Related Art
Today, as a need for a fine circuit pattern has been accompanied by high integration of large-scale integrated circuits (ICs), high semiconductor microfabrication process technology has emerged as a very important issue. To this end, photolithography technology has been developed up to a binary intensity blankmask using a light-shielding film, a phase-shift blankmask using a phase-shift film and a light-shielding film, a hardmask binary blankmask having a hard film and a light-shielding film, etc. so as to improve a resolution of a semiconductor circuit pattern.
By the way, a resist film has recently been continuously required to get thinner in order to achieve high resolution and quality improvement. This is because the thinner resist film causes less scattering of an electron beam while an electron-beam writing process is performed for forming a pattern. However, there is a limit to making the resist film thinner because the resist film is used as an etching mask for forming a pattern of a lower thin film, for example, adjacent thin films such as a light-shielding film, a hard film, etc. and has relatively low selectivity with respect to an etching condition for the lower thin film as it contains major elements of organic substances.
Accordingly, there is a need of improving the properties of the lower film to be etched in order to make the resist film thinner. To this end, a method of increasing an etching speed for the lower film to be etched or a method decreasing the thickness of the lower film to be etched has been proposed.
For example, if the resist film pattern is used in etching the light-shielding film that contains chrome (Cr) as a major element, it is possible to increase the etching speed by plentifully including at least one of oxygen (O) and nitrogen (N) in the light-shielding film. However, the increase in content of one of oxygen (O) and nitrogen (N) makes it difficult to satisfy the optical density, sheet resistance, thickness and the like basic properties required for the light-shielding film. That is, if at least one of oxygen (O) and nitrogen (N) is increased in content, the light-shielding film increases in the sheet resistance and decreases in the optical density, thereby having problems of an electron-charge up phenomenon in an exposure process and deterioration of image contrast. Such problems may be solved by increasing the thickness of the thin film. However, the increased thickness of the light-shielding film increases an aspect ratio of the pattern and causes pattern collapse or the like problem while the pattern is formed.
Accordingly, there is a need of developing a new substance for a light-shielding film which has a higher light-shielding efficiency and a higher etching speed than the existing light-shielding film that contains a compound of chrome (Cr).